The class of computers known as personal digital assistants (PDAS) and laptops are well known in the industry. These types of computer systems are portable, battery operated and may include date-book application programs used to remind their user about meetings, events, appointments, errands, etc. An example of a portable computing device to which the present invention applies is a Palm Pilot, manufactured by Palm, Inc. of Santa Clara, Calif.
Many standard personal computers (PCs) and battery operated computing devices typically go into a low-power consumption sleep mode when there is no user activity. Throughout this disclosure, these computers will be referred to as computing devices whether they are line powered PCs, battery operated laptops, palmtops or a PDA. Power saving strategies may be different in battery operated devices as opposed to line operated computing devices, but both have the goal of reducing energy consumption.
If date-book programs are in use in a computing device, it may be awakened from the low-power state at times programmed into its hardware clock circuit at which time notification procedures may be initiated to remind the user of a pending current date-book event. To remind the user of a pending date-book event, the computing device may display messages on an LCD screen, create sounds using audio circuits within the computing device, cause vibration by activating a motor with an off-center weight attached, or a combination of these techniques may be used. If the user responds to the notification procedure (alarm) (for example, by clearing a message from the display screen), then the computing device may queue the time of the next event into the clock circuit and return to the low-power state. However, if the user is not near the computing device when the alarm goes off, the appointment may be missed.
Computing devices such as PDAs typically program a notification alarm (alarm) to repetitively re-activate after a predetermined time interval (e.g., in another five minutes) and then go into the low power state. After some number of repetitions of activating the alarm (for example, after five attempts to remind the user), the computing device may stop presenting the alarm (in the interest of preserving batteries) until another program event, other than the missed event, becomes current.
The sub-systems required and actions taken during these notification procedures may require considerable energy for a battery operated device. Operating the back-light of an LCD display, running a motor and playing audio through a speaker are some of the most power consuming operations that a computing device performs. Therefore, in cases where the user may be away from the computing device for an extended period of time, the computing device will waste electrical energy by repeatedly attempting to remind the user of a pending event. In addition, the user may not see the reminder until the next time he activates the computing device for some unrelated purpose or until it is time for the next sequential event, both of which may be days later.
There is, therefore, a need for a method and apparatus which enables a computing device to conserve energy with event notification procedures when no user is present to receive the notification.